EFI & Our Powerblock Configuration

Posted: Wed Apr 25, 2007 8:48 am

Customer EFI Inquiry

Quote:

Hi guys,

This enquiry comes to you from Scotland and refers to a UK specification car.

I am re-building a 1969 MGB GT and converting it into a V8, using the Rover 3.9 litre engine and LT77 5-speed transmission. I would like to buy one of your complete wiring harnesses and power blocks for the project. The car will not be standard in a number of ways, and I wondered whether you offered a service to build in any supplementary wiring that is necessary.

Basically, the car will have
Rover Hot-Wire fuel injection from a 1991 Range Rover.
A heated rear window. (Non standard in a UK car from 1969)
A radiator fan.
Stalk mounted dipper-switch and wiper controls, using stalks from a 1980's Mini (not the BMW Mini).

If you are able to alter the standard harness, I can send you any more details that you might need.

Can you please let me know what you can offer, and the price. Thanks in advance, and a very Happy New Year to you all.

Mike
Scotland

Dan's Response

Quote:

Hi, Mike,

I'm certain we can accommodate your needs, probably with little or no modification required to our harness kits. If any mods are required, they should be minor and inexpensive. To be sure, though, please send a copy of the wiring interface needed to the ECU unit, and the wiring for the Mini column switches. We would probably sell you a kit for a later model MGB, as it would have the plugs for the column switches included.

Usually, an EFI systems needs two things to install into an older, non-EFI car, and that's a source of key-switched power, and a source of un-switched power. Every thing else needed would be part of the EFI wiring harness. I'm installing an Edelbrock EFI unit on the Ford 302 engine I'm putting in my own MGBGT, and that's all I have to do to tie it into the main harness.

The heated rear window and the fan are not a problem. We supply a relay for the fan as standard.

If you haven't done so already, please download a copy of the instruction manual for a late model MGB and look it over to see if there's anything you might need that we don't supply. You can download the manual from http://www.advanceautowire.com

Regards,

Dan

Mike's Response

Quote:

Dan, Thanks for your message. I think you are right that only two wires need to be connected to the car's loom to make the EFi work. This is what I have from Geoff King, who has this set up on his car.

The vital connections are these:
Brown (N) supply from a permanently live source.
White/Slate (WS) supply from the ignition circuit for the "ignition on" signal.
White/Purple (WP) output from the relay to the fuel pump - fit an inertia switch in the supply to the pump.
Orange/Black (OB) to earth via a 510 ohm resistor to tell it there is a manual transmission.
There is a single White/Black (WB) wire near the airflow meter. This is the engine speed input from the negative side of the coil connected to the ECU through a 6.8 Kohm resistor within the Rover harness.
So it would appear that only the first two need to interface with the car's harness, although I'm not clear about the fuel pump wiring. You supply a fuel pump relay, so maybe I don't need to connect the WP wire. Any thoughts?

The Mini stalks are shown in the accompanying pictures. I intend to use all the functions, including electric screen wash, except for the horn, which I will have on the steering wheel boss. Can you supply connectors to plug into these stalk plugs? Having compared the Mini diagram with the last model MGB, I think the wire colours are the same on both cars. It's probably the same switch assembly!

Is there anything else you need to know?

Dan's Response

Quote:

Hi, Mike,

On my own car, using an Edelbrock unit, I am running the (brown) main power from the starter solenoid battery connection,and I'm feeding the white/slate) switched power from the fuel pump relay that is supplied with our harness. I also put the inertia switch in this relay circuit, as shown in our instruction manual, so I wouldn't have to cut into the Edelbrock harness.

We don't supply connectors to fit into the Mini connectors, but we can supply new connectors and terminals to replace those on the Mini. You would have to cut off the existing connectors and replace them with ours, and put the mates onto our wiring. There are a total of 14 pins in the Mini harness, but we only have 6-pin and 4-pin connectors, so we would have to supply 1 6-pin and 2 4-pin connectors to make the match. Can you identify the wire colors on the Mini harness? I'm certain they will match up nicely with what the MGB uses, but I would like to mark the diagrams accordingly if they don't.

That should cover everything we need to match up the kit with the EFI unit, but should you run into anything else as you get into it, we can work that out as it arises.

Regards,

Dan

The other wires mentioned would connect up as stated, and would not have any tie in to our panel.

Mike's Response

Quote:

OK Dan,
I think we are getting there. The Mini stalks have the following wiring colours. I've tried to figure out what each cable does, but haven't been 100% successful.

On the lighting stalk, the colours are quite conventional British/Lucas.
Blue - main power from light switch
Blue/White - feed to High Beam
Blue/Red - feed to Dip Beam
Light Green/ Brown - power from flasher unit
Green/White - feed to RH turn signals
Green/Red - feed to LH turn signals
Purple - power input for horn and ?high beam flash?
Purple/Black - feed to horn
As I mentioned, I will want to use the steering wheel boss for the horn switch.
On the wiper/washer stalk, I figured out the following.
Green - main power input
Light Green/Black - feed to washer pump
Red/Light Green - feed to wiper motor ?for low speed?
Blue/Light Green - feed to wiper motor ?for high speed?
Brown/Light Green - also goes to wiper motor, but I don't know for what purpose - ?something to do with parking of blades? Also, how does the flick wipe function connect? Is that the N/LG wire?
I'm quite happy to rewire the stalks into your new connector assemblies, as you suggest. Although there is provision for 14 connections on the stalks, only 13 are used, 8 on the lighting and 5 on the wipe/wash.

One final thing, don't forget this is a UK car with the driver sitting on the right!

Best wishes,
Mike

Dan's Response

Quote:

Purple - power input for horn and ?high beam flash?
Purple/Black - feed to horn
Hi, Mike,

Every thing looks good except I have a question about these two wires. Usually, the purple wire is used for the flash-to-pass feature, and the purple/black wire is grounded to sound the horn. The horns are fed with a constant hot from another purple wire. In Lucas-speak, purple wires are hot all the time, key on or off, and are fused.

Being a RHD car won't make any difference in the wiring harness.

Regards,

Dan

Mike's Response

Quote:

You know your stuff, don't you Dan! It's so nice to deal with someone who genuinely wants to get it right for the customer.

Right I've been looking again at the wiring circuits and testing the switches with my multimeter.

The purple wire is indeed for the high beam flash feature and connects to the Blue/White when the stalk is pulled up.

The Mini horn is connected the other way round, with power going from the push button to the horn via the Purple/Black, and the horn itself is then grounded at its other terminal. So the Purple is the power feed for both horn and flash.

This won't matter in my case as I won't be using the push button on the stalk, so I can leave the P/B wire in your harness out of the connector and route it directly to the steering wheel boss, connecting the horns in the normal MGB fashion.

Is that OK?
Mike

Dan's Response

Quote:

Mike,

We're good to go! You can run the purple/black wire from the steering wheel boss, grounding through the steering column, to the relay in our panel, which will then send power to the horns, the other side of which will be grounded. This is a much safer way of doing business, as there is only power to the horns when the button is depressed, minimizing the opportunities for a short around the horns.

Regards,

Dan

Mike's Response

Quote:

Excellent Dan, can you guys now send me a quote for the kit please, and how you accept payment from overseas, and we'll see if we can do business!

Thanks for your patience.
Mike